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United States Patent |
5,217,388
|
Brown
|
June 8, 1993
|
Wire safety crimp
Abstract
A progressive stamping strip for electrical parts is provided with a spaced
away wire safety crimp. The stamping strip may be used to automatically
crimp leads to both the electrical part and the wire safety crimp. The
wire safety crimp is severed from the stamping strip separate from the
electrical part. The wire safety crimp retains the wires together and
retains them in the plug. The present invention provides an electrical
part with a wire safety crimped on a lead, as well as a molded plug with
the wires protected against exposure from the plug.
Inventors:
|
Brown; Donald C. (Freehold, NJ)
|
Assignee:
|
Heyco Stamped Products, Inc. (Toms River, NJ)
|
Appl. No.:
|
957920 |
Filed:
|
October 8, 1992 |
Current U.S. Class: |
439/455; 439/606 |
Intern'l Class: |
H01R 013/58 |
Field of Search: |
439/455,606,736,865,885
|
References Cited
U.S. Patent Documents
3030694 | Apr., 1962 | Kerstetter et al. | 439/865.
|
4265508 | May., 1981 | Chisholm | 439/885.
|
4266844 | May., 1981 | Chelminski | 439/736.
|
4273409 | Jun., 1981 | Blanche et al. | 439/736.
|
4310213 | Jan., 1982 | Fetterolf, Sr. et al. | 439/453.
|
4428642 | Jan., 1984 | Schwindt et al. | 439/885.
|
4556275 | Dec., 1985 | Hamsher, Jr. | 439/736.
|
4718865 | Jan., 1988 | Cordeiro | 439/606.
|
4790776 | Dec., 1988 | Iljima | 439/695.
|
4854894 | Aug., 1989 | Harrell | 439/606.
|
4897046 | Jan., 1990 | Tengler et al. | 439/579.
|
4911660 | Mar., 1990 | Alf et al. | 439/736.
|
4963699 | Oct., 1990 | Urushibata et al. | 439/867.
|
4973264 | Nov., 1990 | Kamono et al. | 439/498.
|
Primary Examiner: Paumen; Gary F.
Attorney, Agent or Firm: Auslander & Thomas
Parent Case Text
This application is a continuation of application Ser. No. 07/680,341,
filed Apr. 4, 1991, now U.S. Pat. No. 5,176,545.
Claims
Having described certain forms of the invention in some detail, what is
claimed is:
1. In combination an electrical lead, said electrical lead including a
conductor portion, a stamped metal electrical part including a single
crimp end, said crimp end crimped to said conductor portion of said
electrical lead, said crimp end having no extensions therefrom which do
not directly contact said conductor portion, a separate single stamped
metal electrical lead safety crimp part, said stamped metal electrical
lead safety crimp part crimped to said electrical lead, said stamped metal
electrical lead safety crimp part having no extensions therefrom which do
not directly contact said electrical lead, said crimp end and said crimp
part located adjacent and spaced away from each other along said
electrical lead, said lead being bendable between said crimp end and said
crimp part, said stamped metal electrical lead safety crimp part and said
crimp end of said stamped metal electrical part engagable with the molding
plastic of a molded plug, whereby said stamped metal electrical lead
safety crimp part retains said electrical lead in strain relief engagement
within said molded plug.
2. The invention of claim 1 wherein said stamped metal electric lead safety
crimp part when uncrimped is U shaped.
3. The invention of claim 2 wherein the edges of said U are tapered.
4. The invention of claim 1 wherein said stamped metal electric lead safety
crimp part is crimped to the conductor portion of said electrical lead.
5. A molded plastic electric plug including a plastic body, at least one
electrical lead, said at least one electrical lead including a conductor
portion, at least one stamped metal electrical part including a single
crimp end, said crimp end crimped to said conductor portion of said at
least one electrical lead, said crimp end having no extensions therefrom
which do not directly contact said conductor portion, at least one
separate stamped metal electrical lead safety crimp part, said at least
one stamped metal electrical lead safety crimp part crimped to said at
least one electrical lead, said at least one stamped metal electrical lead
safety crimp part having no extensions therefrom which do not directly
contact said electrical lead, said crimp end and said crimp part located
adjacent and spaced away from each other along said at least one
electrical lead, said at least one lead between said crimps end and said
crimp part being bendable before being molded therearound, said at least
one stamped metal electrical lead safety crimp part and said crimp end of
said at least one stamped metal electrical part engaged with the molding
plastic of said plug, whereby said at least one stamped metal electrical
lead safety crimp part retains said at least one electrical lead in strain
relief engagement within said plug.
6. The invention of claim 5 wherein said at least one stamped metal
electrical lead safety crimp part when uncrimped is U shaped.
7. The invention of claim 6 wherein the edges of at least one said U are
tapered.
8. The invention of claim 5 wherein said at least one stamped metal
electric lead safety crimp part is crimped to the conductor portion of
said at least one electrical lead.
Description
BACKGROUND OF THE INVENTION
The present invention is a metal stamped wire safety crimp strain relief
for an electrical part.
In the electrical industry it has been found very effective to be able to
manufacture electrical parts in progressive stamping operations. A strip
of metal can progressively pass through successive stamping steps to be
formed into a desired electrical part. The electrical part can be left
connected to the stamping strip. The stamping strip can then be used
directly either off the original stamping machine or from a coil of
attached stamped electrical parts and be fed into an automated crimping
operation.
The progressive stamping operation alone provides many opportunities for
economies. The art is well developed. Speed of production is one dividend
of progressive stamping. Another dividend is that metal can be stamped to
have strengths equivalent to solid electrical parts but economically
produce effective metal electrical parts with less metal. Stamping also
saves the cost of expensive manual labor. Progressive stamping enables
automation of the making of the electrical parts.
Automated crimping has its foibles too. Wire can be crimped to electrical
parts from a strip and be ready for further operations such as molding
into plugs. The crimped wires can be placed in molds by automation also.
An important need for electrical parts connected to wires, leads, cord,
and/or cables is wire safety and strain relief. The usability of
electrical parts in plugs requires that wires provide electrical integrity
and safety. Safety requires that the strands of wires are not likely to
rip loose nor be exposed from plugs. Part of wire safety of connected
electrical parts depends upon strain relief. The attaching crimp of the
wire itself can protect the wire from strain in some measure. The molding
of crimped electrical parts into a plug provides some further wire safety
and strain relief. Wire safety and strain relief is always an important
consideration in terms of integrity, cost and effectiveness of electrical
parts and plugs.
Plugs on long cables are notoriously vulnerable to the temptation of being
detached by a remote tug on the cable ultimately detaching wires and
possibly exposing them. Such pulling is a great test for the best of wire
safety systems and strain reliefs. The present invention provides a new
and better, simple wire safety crimp. The creation of effective wire
safety crimps and strain reliefs in a progressive stamping operation is
very complex.
The present invention provides an effective efficient wire safety crimp on
a stamping strip with a strain relief that can function in the environment
of a progressive stamping operation, automated crimping and for use with
molded plugs.
DESCRIPTION OF THE RELATED ART
The prior art discloses many different electrical parts crimped to wires,
leads, cords and/or cables with various forms of strain reliefs and
various molded plugs which by their configuration provide wire safety and
strain relief. U.S. Pat. No. 4,854,894 discloses a typical molded plug
where the electric terminals are crimped to conductors. The electric cord
extends centrally from the molded plug. In this configuration, there is
some strain relief from a strain on the conductor, since strain must pass
through the molded plastic of the plug to the spread apart terminals so
that there is no direct strain on the conductor in the crimp of the
terminal.
U.S. Pat. No. 4,790,776 discloses an molded plug similar the plug in U.S.
Pat. No. 4,854,894. The blades are crimped to the conductors forming a V
shaped separation in the plug so that strain has to be taken up by the
molded plug. In FIG. 5(A) the terminal blades can be seen on a typical
prior art stamping strip which can be used in the machine crimping of the
blades to the conductors. The blade are firmly held to protect against
their being ripped out and exposing wires.
U.S. Pat. No. 4,718,865 discloses a crimped electrical terminal blade with
two crimpable portions on the blade. The second crimp provides a wire
safety crimp for the attached conductor wire insulation. Both crimps are
connected and extend from the blade. There is no flexibility as between
the two crimps. The crimps are also aligned so that a linear tug on the
conductor is in line with both crimps. The terminal and the conductor are
in a separate housing which is then molded into the plug. The separation
of the housing in the plug may provide some additional wire safety. The
structure is complex and requires extra steps for assembly. U.S. Pat. No.
4,963,699, FIG. 4, discloses a somewhat similar wire holding
configuration.
U.S. Pat. No. 4,273,409 discloses a two piece crimp on a conductor,
crimping a wire, the crimp, having a double sided configuration, crimping
the conductor wire flush to the back of a terminal tongue. This
configuration does not provide any secondary wire safety but the wires are
strongly protected by the single crimp.
U.S. Pat. No. 4,266,844 discloses an intricate system, including a double
crimp within a ferrule sleeve 46 where conductor wires are spaced away
from terminals by conductors 50, whose U shaped sections may serve as a
strain relief within a plug. This is exemplary of the wire safety crimp
and strain relief of enclosed electrical conductors and terminals within a
plug configuration.
U.S. Pat. No. 4,973,264 discloses flat cable 50 in FIG. 2 in a non linear
crimp configuration within a housing, functioning as a wire safety and
strain relief in a single configuration.
U.S. Pat. No. 4,556,275 discloses a C shaped single, crimpable wire safety
and strain relief for insulation in a housing. The parts are attached to
each other.
U.S. Pat. No. 4,897,046 in FIG. 4, shows a molded wire safety 24.
SUMMARY OF THE INVENTION
The present invention is a stamped wire safety crimp for a conductor cable,
lead, cord or wire, particularly for a lead wire molded in a plug. The
wire safety crimp connects to either the conductor cable, lead, cord or
wire and forms a wire safety crimp in the molded plug.
In a preferred embodiment, the present invention includes a continuous
stamped strip of electrical parts, including a crimp for connecting an
electrical part to a conductor wire and a wire safety crimp for the
conductor cable, lead, cord or wire, preferably the wire. The wire safety
crimp is spaced away and unconnected to the electrical part on the
stamping strip, yet crimpable to the conductor cable, lead, cord or wire,
particularly in a machine crimping operation.
The stamping strip of the present invention is made substantially in a
prior art progressive stamping operation wherein metal electrical parts
are progressively stamped and shaped. The stamped, shaped metal electrical
parts are produced, joined on a metal stamping strip. The stamping strip
of the present invention includes a longitudinal retaining strip with
intermediate spaced away linking strips. The stamping strip, therefore,
includes the electrical parts connected by integral, links between each
part. The metal electrical parts include the conventional crimp with a
spaced away, aligned crimpable portion, which may be simultaneously
crimped to the conductor cable, lead, cord or wire in a machine crimping
operation. The machine crimping operation strips off the connecting metal
parts and provides the metal electrical part connected to the conductor
wire, with a circumferential wire safety crimp on the conductor cable,
lead, cord or wire, which may freely bend with the bends in the conductor
wire.
In the manufacture of the continuous metal stamping strip, the completed
electrical parts on the stamping strip are usually wound onto a reel, so
that they can be available to be machine fed for an automated crimping
operation.
Once the conductor cable, lead, cord or wire has been crimped with its
metal wire safety crimp, the conductor cable may then be molded into a
plug for use.
In conventional molding, the molding of the plastic of the plug, in itself,
acts somewhat as a wire safety crimp. Where there is a plurality of cords
in a plug, the individual conductor cords or leads, generally coming from
electrical cable, are separated within the plug, which generally forms a V
shaped relationship as between the cable and the individual cords. Thus,
flexure and strain on the cable in the prior art generally is indirect
because of the angulation as between the strain on the cable and the
position of the conductor wire.
In the present invention, the angulation is the same, but the wire safety
crimp, holds all of the strands of the wire. The wire safety crimp is
embedded in the molded plastic, and is strongly engaged in the plastic of
the plug and strongly hold the wires so that even a loose strand is not
likely to be able to be pulled out of the plug and exposed.
The simplicity of the structure and the simplicity and the strength of the
wire safety crimp provide inexpensive, unexpected wire safety in the
environment of the conventional, automated crimping wires and molding them
into plugs.
According to the present invention a stamping strip for the progressive
stamping of electrical parts for crimped engagement to an electrical lead
in a plastic molded electric plug is provided. The stamping strip has an
end strip extending along the length of the stamping strip. A wire safety
crimp extends inward from the end strip. There is stamped electrical part
in the stamping strip which includes a crimp end. The stamped electrical
part crimp end and the wire safety crimp are aligned and spaced away from
each other. There is a lateral spacer spaced away from the wire safety
crimp and the stamped electrical part crimp end on the end strip. The
lateral spacer extends inward from the end strip. A link extends from at
least one of the stamped electrical parts. The lateral spacer integrally
joins the end strip and the link. The crimp end when conductively crimped
to an electrical lead and the wire safety crimp when crimped to the
electrical lead are separate and spaced away from each other along said
electrical lead when the end strip and the lateral spacer and the link are
severed from the stamping strip.
The stamping strip may include a projection linking the wire safety crimp
and the end strip. The wire safety crimp be U shaped and the edges of the
U may be tapered. The wire safety crimp and the crimp end both may be U
shaped and the edges of the U's may be tapered. The stamping strip may
include at least two wire safety crimp portions and electrical parts with
crimp ends and also at least one link connecting the stamped electrical
parts and at least one lateral spacer connecting the link.
The present invention includes the combined stamped electrical part, a wire
safety crimp part and an electrical lead, all for molding into an electric
plug. The stamped electrical part including the crimp end is crimped to
the safety wire electrical lead. The wire safety crimp part is crimped
near the crimp end, separate and spaced away from the crimp end. The wire
safety crimp part is separately engaged by the molding plastic when molded
in a plug to retain the electrical lead conductor wire in the plug. The
uncrimped wire safety crimp part may be U shaped and the edges of the U
may be tapered.
The present invention includes a molded plastic electric plug with a
plastic body, at least one stamped electrical part, at least one wire
safety crimp part, and at least one electrical lead. At least one stamped
electrical part includes a crimp end, crimped to the conductor of at least
one electrical lead. At least one wire safety crimp part is crimped to at
least one electric lead near a crimp end. The wire safety crimp is spaced
away from at least one crimp end is separate and engaged by the molding
plastic of the plug so that the wire safety crimp part retains the
conductor wire in the plug. At least one uncrimped wire safety crimp part
may be U shaped and tapered.
Although such novel feature or features believed to be characteristic of
the invention are pointed out in the claims, the invention and the manner
in which it may be carried out, may be further understood by reference to
the description following and the accompanying drawing.
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 is a broken away plan view of a stamping strip including a metal
wire safety crimp of the present invention.
FIG. 2 is a side elevation of FIG. 1.
FIG. 3 is a right end elevation of a single electrical part of FIG. 1.
FIG. 4 is a schematic of a stamping strip, such as shown in FIG. 1, being
taken up on a reel.
FIG. 5 is a plan view of an electrical part, such as shown in FIGS. 1
through 3, crimped onto a conductor wire.
FIG. 6 is a section through a molded plastic plug, including two crimped
electrical parts of FIG. 5.
Referring now to the figures in greater detail, where like reference
numbers denote like parts in the various figures.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The stamping strip 10 has an end strip 11, from which extends shaped wire
safety crimps 12. Between the wire safety crimps 12 on the end strip 11 is
a cross piece 13, which joins the electrical part link strip 15 to the end
strip 11. The link strip 15 joins the electrical part female receptacles
16, which are attached to the stamping strip 10. As can be seen in FIG. 1,
the female receptacles have crimp ends 14, a first leg 17 has a first fold
18 and a second fold 19. There is a second leg 26.
The first and second folds 18, 19 are integrally joined to the second leg
at fold lines 27.
The wire safety crimp 12 extends from a projection 28 on the end strip 11.
As can be seen in FIG. 3, the wire safety crimp 12 has a U shaped
configuration with tapered edges 20.
The first leg 17 and second leg 26 are rigidized by spines 21 stamped into
the legs 17 and 26. In the female receptacle 16, exemplified in the
drawings, the female receptacle 16 has flared end 22. The crimp end 14 of
the female receptacle 16 is U shaped with a tapered crimp end 23, similar
to the crimp end 20 on the wire safety crimp 12.
The female receptacle 16 has cambered portions 24, spacing the legs 17 and
26 apart, so that they can join in spring like engagement at the flared
end 22. The flared end 22 comprises leg ends 25 on the legs 17 and 26,
forming a V shape to guide a male electrical part into electrical contact
when in use.
In FIG. 4, female receptacles 16 are seen being wound up on a reel 29, as
they come off a stamping machine.
In FIG. 5, a female receptacle 16 is shown, having been stamped and crimped
to a strip wire 30 from a cord 31 in a cable 33.
As shown in FIG. 5, the female receptacle 16, is shown after passing
through an automated stamping and crimping operation. The ends of the link
strip 15 are severed and the tapered crimp edges 20 and 23 are stamp
crimped and curled around the wire 30. As can be seen, the crimp 14 is
connected to the wire 30, while the wire safety crimp 12 is spaced away on
the wire 30, firmly crimping and holding the wire 30, but flexible to
movement of the wire 30.
As shown in FIG. 6, the two female receptacles 16 are molded into a plastic
plug 32. Two cords 31 extend from a cable 33. The wires 30 are crimped to
crimp ends 14. The wire safety crimp 12 are also crimped to the wire 30.
The female receptacles 16 are spaced apart, positioned to normally receive
the electrical male connector (not shown). As can be seen, the spacing
apart necessitates the cord 31 with the wires 30 and the wire safety crimp
12, to form a V shape.
OPERATION
The stamping strip 10 is typical of a progressive stamping and folding
operation for the manufacture of electrical parts. The female receptacle
16 is a typical stamped and folded electrical part made by a progressive
stamping operation. In FIG. 1, the electrical part is a female receptacle
16 with a crimp end 14. No novelty is claimed or suggested with regard to
the structure of the receptacle 16 with its crimp end 14.
In the manufacture of electric plugs, for instance, a common procedure is
to take a strip of electrical parts held together on a stamping strip 10,
generally on an end strip 11, wound up on a reel 29, and then feed the
stamping strip 10 into an automated crimping operation, which separates
the electrical parts, stamps off the linking parts and crimps the
electrical parts to wires, such as shown in FIG. 5. The crimped electrical
parts are attached to the wires forming cord sets, which are then placed
into plastic molds for the formation of plugs, such as plug 32, as shown
in FIG. 6.
The present invention spaces apart on the conventional stamping strip 10, a
wire safety crimp 12. The wire safety crimp 12 extends from the stamping
strip 10 on a projection 28.
In a usual stamping and crimping operation, wires 30 are automatically
placed in crimps ends 14 and wires 30, or the insulated cord 31 is placed
in the wire safety crimp 12, and linking end strip 11, projection 28 cross
piece 13 and linking strip 15 are severed from the stamping set and the
crimp end 14 and the wire safety crimp 12 are crimped. A clean electrical
part, such as shown in FIG. 5, results from this operation.
The stamping strip 10 has cross pieces 13 joining the end strip with the
linking strip 15. Thus, in the stamping operation, the laid wire 30 is
simultaneously joined to the spaced apart crimps 12 and 14, which are now
independent of each other.
In the prior art, among other things, double crimps have been provided to
provide wire safety. Such crimps generally are connected to each other,
one of which commonly is crimped to the wire and the other crimped to the
wire or wire insulation to act as a wire safety. Typical of such devices
is the double crimp, as shown in U.S. Pat. No. 4,718,865. While double
crimps are effective in providing wire safety, they are necessarily joined
to each other and inflexible. The joined double crimp has the advantage of
being easily adapted to a machine crimping operation, but the linkage
between the two crimps generally renders them inflexible.
The molding of a crimped wire with just a single crimp, similar to the
molding of a wire in a plug, such as shown in FIG. 6, does provide some
degree of wire safety with the plastic of the plug also holding the wire
and/or the wire insulation in the grasp of the molded plastic. When more
than one conductor cord 31 is molded into a plug 32, the wires are
generally separated, as shown in FIG. 6, so that a normal tug on a cable
would be directed through an angulated wire before straining the actual
wire to electrical part connection.
The present invention, by having a separated wire safety crimp, has the
advantage of being able to use the natural flexibility of the wire between
the crimps. There is no linkage between the two crimps. Therefore, when
molded into a plug 32, such as shown in FIG. 6, the conductor wire 30 and
the cord 31 are easily bent, and strongly held together by the wire safety
crimp 12, so that the strain relief crimp 12 in this type of usage is not
in linear alignment with the wire crimped 30 crimped to the crimp end 14.
Thus, the angulation of the wire alone provides an extra modicum of strain
relief. The cord 31 in effect may be a lead including insulation and a
wire 30.
The bulk of the wire safety crimp 12, in this instance, angulated away from
the crimp 14, also serves to be grasped by the plastic in the plug 32. All
strain must necessarily pass through the wire safety crimp 12 first, which
is crimped to and engages all the wire strands, so that no basic weakness
in the strands themselves is likely to give under the strain nor are
broken or loose strands of wire likely to be pulled out of the body of the
plug 32 and exposed. The bulk of the wire safety crimp 12 also provides
extra strain relief because of its engagement in the plastic.
The present invention provides an inexpensive, non bulky, effective,
flexible wire safety, not heretofore available in the spaced apart
relationship, which enables it to also be machine crimped.
The terms and expression which are employed are used as terms of
description; it is recognized, though, that various modifications are
possible.
It is also understood the following claims are intended to cover all of the
generic and specific features of the invention herein described, and all
statements of the scope of the invention which, as a matter of language,
might fall therebetween.
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